Time delay motor starting system



June 22, 1965 c. w. REED 3,191,114

TIME DELAY MOTOR STARTING SYSTEM Filed Sept. 26, 1962 United StatesPatent 3,191,114 TIME DELAY MOTOR STARTING SYSTEM I Charles W. Reed,Taft, Califi, assignor to Socony Mobil Oil Company, Inc., a corporationof New York Filed Sept. 26, 1962, Ser. No. 226,278

2 Claims. (Cl. 318-472) This invention relates to the sequential andautomatic starting of a plurality of well pump motors in an oil fieldand more particularly to a control system for starting a well pump motorat a predetermined time delay after power has been applied to thesystem. i

In the operation off-present day oil fields having a plurality of wellsoperated by electric pump motors, control systems are employedautomatically and sequentially to start the Wells after they have beenshut down, for example, from power failure. The sequential startingoperations prevent the power transformers utilized from being burned outby an excessive load due to starting currents which may occur if thewells were all started at the same time. p r t 1 Difliculties have beenencountered, however, in applying the sequential starting operation tothe larger pumps for the following reason. The control systems forstarting the motors sequentially and automatically include circuitshaving delay devices for delaying the application of power to thestarting units. The starting units necessary for the larger pumpsrequire a large amount of current for actuation which in some cases ismore than the available delay devices can handle. This excessive orlarge amount of current will cause the delaydevices to burn out whenapplied thereto. t

In accordance with the present invention, a time delay starting systemcoupledto power supply means is pro vided which protects the delaydevice utilized from the large current required by the pump motorstarting unit. The system includes. a first relay control means forapplying starting and running power to the motor. A time delay circuitisprovided having a normally open first switch means which is closed aftera predetermined time delay following application of current to said timedelay means. The time delay circuit has input and output ends coupled tothe first switch means and a current rating less than that of the firstrelay control means. An energizing circuit is coupled to the powersupply means and to the input end of the delay circuit. A shuntingcircuit is provided having a second switchmeans. The

x shunting circuit has .a first end coupled to the energizing circuit ata point between the power supply means and the time delay circuit and asecond end coupled to the first relay control means. A second relaycontrol means of current rating within the current limits of said delaycircuit is provided for applying energizing current to the first relaycontrol means'to start the motor. This second means is coupled to theoutput end of the time delay circuit and is responsive to currentpassing from the energizing circuit by wayof the first switch means whenclosed for closing the second switch means to complete the shuntingcircuit to the first relay control means, thereby shunting out thetimedelay circuit before applying energizing current to the first relaycontrol means.

For a more complete understanding of the present invention and forfurther objects and advantages thereof, reference may now be had to thefollowing description taken in conjunction with the accompanyingdrawing. This drawing illustrates an oil field having a plurality ofpumps each of which has an automatic control system for starting itsassociated well at a predetermined time delay after power is applied tothe system.

Control circuits -14 are provided respectively for the motors 60 and64-67 of pumps 70-74. Power supply Patented June 22, 1965 ICC that thewell pumps are started in sequence with a sumcient time period betweenthe start of each pump so as to avoid overloading the power transformer.

To carry out this operation, each control circuit has associatedtherewith a starting circuit which includes a time delay device 34, asillustrated in the control circuit 10, for delaying the startingoperation of each pump. Each of the time delay devices can be arrangedwith a different delay time. As an example, the delay difference can beanywhere from 5 to 30 seconds.

A starting or power relay 28 is provided to apply starting and runningpower to the motor 60 after the time delay. If the motor 60 is a largemotor, for example 25 horsepower or more, a large starting relay 28 isrequired. This relay draws a large amount of current upon actuation.

To protect the delay device 34 fromthe large current,

requirementsof relay 28, a shunting circuit is provided 6 which includesconductors 46 and 47. A small relay.

39 is provided in series with the delay device 34 and is actuated afterthe delaying operation of device;34 to complete the shunting circuit toshunt the delay device 34 and to apply energizing current to the powerrelay 28. The relay 39 can be actuated without adversely affecting thedelay device 34 since it draws only a small amountof current, the valueof which is below the maximum limit that the delay device 34 can safelyhandle. With the arrangement illustrated the delay device 34 performsitsdelaying function and then is shunted out before the relay 28 isactuated, thereby protecting the delay device 34 from the large currentrequirements of relay 28.

There now will be described more specifically the manner in which the;circuit 10 operates. The power transformer 15 normally supplies 440volts to the motor 60 byway of power lines 16-18, conductors 19-21, andrelay control terminals 22-24 which are normally closed by switches25-27 coupled to starting relay 28 by way of linkage representedbydotted line 30.

if the motor 60 has been shut downfor some reason, the starting relay 28is actuated, aitera predetermined time delay, to start the motor 60. Thetime delay is determined by the delay device 34 which preferablyis athermal-delay device. Initially, power is applied or current flowsthrough thedelay device 34 to the relay 39. This how of current is bywayof conductors 19 and31, closed switch 32, conductor 33, line-droppingresistor 35, and through heating element or resistor 36 of delay device34. From resistor 36, current flows to conductor 20 by way of conductor38, coil 40 of relay 39 and conductor 59. During this time, the voltageapplied to the coil 40 of the relay 39 is not sufiicient to actuate therelay.

As current flows through the element or resistor 36, its temperatureincreases. When a predetermined temperature is reached, the bimetallicelements comprising the switch contacts 37 close to shunt theline-dropping resistor 35 and the heating element or resistor 36 wherebysuificient current is applied to the coil 40 to actuate the relay 39.When the coil 40 of the relay 39 is energized, the switches 41 and 43,which are coupled to the coil 40 by way of linkage represented by thedotted line 42, are actuated to contact respectively terminals 44 and45. When this occurs, the shunting circuit including conductors 46 and47 is completed across closed switch 43 thereby allowing energizingcurrent to be applied to the coil 29 of relay 28. The circuit from thecoil 29 to conductor 20 may be traced by way of conductors 51 and 50.When the coil 29 of relay 28 is energized, the switches 25-27 areactuated to contact terminals 22-24.

Thus 440 volts are applied to the motor oil to operate the pump 70 byway of connection 61. With the arrangement provided, the delay device 34thus performs its delaying operation and then is shunted out before therelay 28 is actuated.

Means are also provided for maintaining the relay 39 in its actuatedcondition upon the completion of the shunting circuit. This comprises. acircuit which includes conductor 48 coupled from conductor 19 to one ofthe terminals 44 and also conductor 49 coupled from the other of theterminals 44 to the conductor 38. Thus, when relay 28 is actuated,energizing current is applied to the coil 40 of relay 39 by way ofconductors 19 and 48, closed switch 41, and conductor 49.

The other pumps 71-74 may be started in a like manner. If a powerfailure should occur, the pumps will be stopped; but upon resumption ofpower, the pumps will again be brought into operation sequentially inthe manner described.

In event it is desired manually to start the well for one reason oranother, for example, to reposition the sucker rod 62 or to repositionthe counter balance 63, switch 52 can be closed, thereby opening switch32. This completes a circuit to the relay 28 by way of conductor 54,closed switch 52, and conductor 53 which circuit shunts the time delaydevice 34 to allow 440 volts to be applied to the starting relay 28.

In one embodiment, the coil 29 of the starting relay 28, when actuated,draws about 5.75 amperes and the coil 40 of the relay 39, when actuated,draws about .75 amperes. The contact rating of the delay device 34 is ofthe order of 1 ampere at 220 volts.

While the invention has been described in connection with one embodimentthereof, it will now be understood that modifications will suggestthemselves to those skilled in the art, and it is intended to cover suchmodifications as fall within the scope of the appended claims.

What is claimed is:

1. A motor control system coupled to power supply means for starting anelectric motor comprising:

' .a first relay control means for applying starting and running powerto said motor,

a time delay circuit having a normally open first switch means which isclosed after a predetermined time delay following application of currentto said time delay means,

said time delay circuit having input and output ends coupled to saidfirst switch means,

' the current rating of said time delay circuit being less than that ofsaid first relay control means,

an energizing circuit coupled to said power supply means and to saidinput end of said time delay circuit,

a shunting circuit including a second switch means,

said shunting circuit having a first end coupled to said energizingcircuit at a point between said power supply means and said time delaycircuit and a secend end coupled to said first control means,

a second relay control means of current rating within the current limitsof said delay circuit for closing said second switch means independentlyof said first relay control means,

All

said second relay control means being coupled to sai output end of saidtime delay circuit and responsive to current passing from saidenergizing circuit by way of said first switch means when closed forclosing said second switch means to complete said shunting circuit tosaid first relay control means to shunt said time delay circuit and toapply energizing current to said first relaycontrol means.

2. In a system for starting sequentially a plurality of electric pumpmotors in an oil field wherein a control system coupled to power supplymeans is provided for each of said pump motors for starting itsassociated motor at a predetermined time delay after power is appliedthereto, a motor control system comprising:

a time delay circuit having a normally open first switch means which isclosed after a predetermined time delay following application of currentto said time delay means,

said time .delay circuit having input and output ends coupled to saidfirst switch means,

an energizing circuit coupled to said power supply means and to saidinput end of said time delay circuit,

a starting relay having a control winding for applying starting andrunning power to its associated motor,

the current rating of said time delay circuit being less than that ofsaid control winding of said starting relay, 7

a shunting circuit including a second switch means,

said shunting circuit having a first end coupled to said energizingcircuit at a point between said power supply means and said time delaycircuit and a second end coupled to said control winding,

- a second relay having a control winding of current rating within thecurrent limits of said time delay circuit coupled to said output end ofsaid time'delay circuit and responsive to current passing from saidenergizing circuit by way of said first switch means when closed forclosing said second switch means to complete said shunting circuit toshunt said time delay circuit and to apply energizing current to saidstarting relay,

an operating circuit coupled to said motor and to .said control windingof said second relay for applying energizing current thereto whenrunning power is applied to said motor, and

means actuated by said second relay for completing said operatingcircuit to said second relay at the same time that said shunting circuitis completed.

References Cited by the Examiner UNITED STATES PATENTS ORIS L. RADER,Primary Examiner.

1. A MOTOR CONTROL SYSTEM COUPLED TO POWER SUPPLY MEANS FOR STARTING ANELECTRIC MOTOR COMPRISING: A FIRST RELAY CONTROL MEANS FOR APPLYINGSTARTING AND RUNNING POWER TO SAID MOTOR, A TIME DELAY CIRCUIT HAVING ANORMALLY OPEN FIRST SWITCH MEANS WHICH IS CLOSED AFTER A PREDETERMINEDTIME DELAY FOLLOWING APPLICATION OF CURRENT TO SAID TIME DELAY MEANS,SAID TIME DELAY CIRCUIT HAVING INPUT AND OUTPUT ENDS COUPLED TO SAIDFIRST SWITCH MEANS, THE CURRENT RATING OF SAID TIME DELAY CIRCUIT BEINGLESS THAN THAT OF SAID FIRST RELAY CONTROL MEANS, AN ENERGIZING CIRCUITCOUPLED TO SAID POWER SUPPLY MEANS AND TO SAID INPUT END OF SAID TIMEDELAY CIRCUIT, A SHUNTING CIRCUIT INCLUDING A SECOND SWITCH MEANS, SAIDSHUNTING CIRCUIT HAVING A FIRST END COUPLED TO SAID ENERGIZING CIRCUITAT A POINT BETWEEN SAID POWER SUPPLY MEANS AND SAID TIME DELAY CIRCUITAND A SECOND END COUPLED TO SAID FIRST CONTROL MEANS, A SECOND RELAYCONTROL MEANS OF CURRENT RATING WITHIN THE CURRENT LIMITS OF SAID DELAYCIRCUIT FOR CLOSING SAID SECOND SWITCH MEANS INDEPENDENTLY OF SAID FIRSTRELAY CONTROL MEANS, SAID SECOND RELAY CONTROL MEANS BEING COUPLED TOSAID OUTPUT END OF SAID TIME DELAY CIRCUIT FOR CLOSING TO CURRENTPASSING FROM SAID ENERGIZING CIRCUIT BY WAY OF SAID FIRST SWITCH MEANSWHEN CLOSED FOR CLOSING SAID SECOND SWITCH MEANS TO COMPLETE SAIDSHUNTING CIRCUIT TO SAID FIRST RELAY CONTROL MEANS TO SHUNT SAID TIMEDELAY CIRCUIT AND TO APPLY ENERGIZING CURRENT TO SAID FIRST RELAYCONTROL MEANS.